Get difference between 2 dates in JavaScript

How to get the difference between 2 dates in JavaScript?

let startDate = new Date('2020-10-07');
let endDate = new Date('2020-11-12');

const DAY_IN_MS = 24 * 60 * 60 * 1000;
let timeDiff = Math.abs(endDate.getTime() - startDate.getTime());
let dayDiff = Math.ceil(timeDiff / DAY_IN_MS);

console.log('Difference is: ' + dayDiff + ' days');

The getTime() method returns the number of milliseconds since the Unix Epoch.

Note: JavaScript uses milliseconds as the unit of measurement, whereas Unix Time is in seconds.

getTime() always uses UTC for time representation. For example, a client browser in one timezone, getTime() will be the same as a client browser in any other timezone.

You can use this method to help assign a date and time to another Date object. This method is functionally equivalent to the valueOf() method.

getTime() manual